Thickness Ridge Cloudiness is a system with the appearance of a band of cloud which can be found in the thickness ridge ahead of a frontal cloud band. There are often convective clouds in the summer season. The cloudiness in the thickness ridge may be associated with the frontal system in its northern parts or may be separate. No characteristic life cycle can be observed in the cloud features of a Thickness Ridge Cloudiness.

Appearance in METEOSAT:

• IR imagery:
  • Mostly fibrous and/or dense cloudiness, white or light grey;
  • cellular features within the cloud band indicating embedded convection;
• WV imagery:
  • The cloud features in the IR image can be seen as white features in an extended grey area;
  • for some cases a distinct black zone appears between the frontal cloud band and the Thickness Ridge cloud band.
• VIS imagery:
  • The VIS image generally shows light grey shades, representing middle to high translucent clouds, with white spots indicating embedded convection cells.

The previous three images show a representative case over the Baltic Sea. In the IR image high fibrous clouds with a bright white signal can bee seen. The WV channel shows a light grey field of strong humidity at upper levels with enclosed white patches. In the visible channel fibrous light grey cloudiness is seen; furthermore, there is a significant separation between the frontal cloud band and the Thickness Ridge cloud band.
In this example, there is no significant convective activity. The images above show another example for Thickness Ridge Cloudiness over Southern Scandinavia and the Baltic Sea. A dark zone in IR and WV clearly indicates a separation between the two cloud systems.